RELIANCE WATER HEATERS GUF-50 1**

This site computed the 242 therms figure; the registry does not state it. The calculation starts from the registry's UEF, the ratio of hot water delivered to energy used. For this model the UEF is 0.7, applied to the DOE test's daily hot-water draw for the high draw pattern. The registry values come from the DOE CCD, retrieved 2026-09-19. At that draw, the model ranks 90th lowest energy use of 414. That places it in the lowest quarter of its class for energy use. The figure holds at the test's draw only; an annual figure at other daily draws is not available here. The steps are set out in how the annual cost is calculated.

The high draw pattern describes a larger household, or one where showers and laundry overlap. The model's first hour rating, the gallons of hot water available in the first hour from a full tank, is 83 gallons. Its rated volume is 48 gallons. A home whose hot-water use matches the high pattern is the case the 242 therms figure describes. A home with lighter or heavier daily use falls outside that test condition, so the figure is a reference, not a forecast. To compare other fuels or sizes, use the selector by fuel, space and size. A same-class alternative can be found with a replacement search by model number.

The running cost is not stated in this text, because it depends on your state's average residential gas price. The page computes it from your ZIP, and the same calculation is available in the cost calculator on your own ZIP. The 18 therms gap below the 260 therms class median is an energy difference at the test's draw. What that gap is worth each year also depends on your rate, so it is not given here. A seller or plumber checking a listing can match the 242 therms figure and the 0.7 UEF against the DOE CCD entry for GUF-50 1**. The installed-cost range on this page sits in its own block, with its source and date. It is a modeled range, not a quote.